<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		ul{
			list-style: none;
			display: flex;
			height: 300px;
			width: 600px;
			margin:  200px auto;
		}
		li:hover{
			flex:20;
		}
		li{
			flex:1;
			transition: all 1s;
		}
		li:nth-child(1){
			background-image: url("http://www.yangod.com/wp-content/uploads/2016/06/71e00091b96929c94ff.jpg");
		}
		li:nth-child(2){
			background-image: url("http://dostatic.pctowap.com/doimg/n.sinaimg.cn/sinanews/20160705/IG5K-fxtsatm1394805.jpg");
		}
		li:nth-child(3){
			background-image: url("http://dingyue.nosdn.127.net/79zWZw8PcoftJCgaBedB2XutzaLupZDFsjQKOlL51z2Zm1469714656050.jpg");
		}
		li:nth-child(4){
			background-image: url("http://dostatic.pctowap.com/doimg/n.sinaimg.cn/games/20160627/ODzO-fxtmwep2792618.jpg");
		}
		li:nth-child(5){
			background-image: url("http://down.52pk.com/uploads/allimg/151203/15423522S-2.jpg");
		}

	</style>
</head>
<body>
	<ul>
		<li></li>
		<li></li>
		<li></li>
		<li></li>
		<li></li>
	</ul>
</body>
</html>